The present technology relates to an addition ratio learning apparatus and method, an image processing apparatus and method, a program, and a recording medium and particularly, to an addition ratio learning apparatus and method, an image processing apparatus and method, a program, and a recording medium that enable a high noise reduction effect to be obtained with respect to all images.
In a video signal of a motion picture, similar image information is repeated with a frame period and a correlation between frames is very strong. Meanwhile, because the video signal does not correlate with encoding distortion or noise components, if the video signal is time-averaged in units of frames, signal components is almost unchanged and only the distortion or noise components decrease. Therefore, the distortion or noise can be reduced.
As an apparatus that reduces the noise using a characteristic of the video signal, a frame circulation noise reducing apparatus that reduces the noise while detecting a motion of an image one frame before and compensating for the motion is known.
The noise reducing apparatus in the related art is configured to change an addition ratio according to motion components of an image or an amount of noise included in the image, weight-average a pixel of a current frame and a corresponding pixel of a previous frame on the basis of the addition ratio, and generate an output video signal. Therefore, the motion compensated corresponding pixel is cumulatively weight-averaged and the noise can be reduced while a residual image is prevented from being generated.
In addition, technology for adding a plurality of images while performing motion compensation, executing noise reduction processing of a temporal direction, and executing the noise reduction processing of a spatial direction in one image with respect to each image before the addition has been suggested (for example, refer to Japanese Laid-Open Patent Publication No. 2010-171753).
According to the technology that is disclosed in Japanese Laid-Open Patent Publication No. 2010-171753, the strength of the noise reduction of the spatial direction can be changed with respect to the plurality of images to be added, and the noise can be reduced and the signal components can be preserved when in-plane NR processing and addition NR processing are executed.
In addition, technology for counting a field number and a frame number after a signal level rapidly changes in an input video signal and dynamically controlling an addition ratio such that the addition ratio gradually increases according to a count value has been suggested (for example, refer to Japanese Laid-Open Patent Publication No. 2007-329524).